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June 16, 2009 2:20PM (UTC)

In May, when President Obama announced tougher fuel-economy standards for cars, trucks and SUVs, pundits on the right accused him of endangering the lives of American drivers.

"Proposed mileage standards would kill more Americans than the Iraq War," thundered libertarian Steve Milloy. Michelle Malkin lamented the laws' "potentially lethal impact." At National Review, Iain Murray argued the new policy amounts to "blood for less oil." At the core of conservatives' objection is the assumption that the automakers will attempt to meet the new regulation by selling smaller cars -- and smaller cars kill.

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This critique is as wrongheaded and outdated as the Edsel. To begin with, the new rules won't drastically downsize the American fleet. The regulations assign different fuel-economy targets to different classes of cars based on size. Smaller, lighter models have to get more miles per gallon than bigger, heavier ones. While the industry as a whole will aim for the new 35.5 mpg standard, each automaker's fleet won't have to hit that target. That means automakers won't scrap SUVs and pickups for compacts, but will simply strive to make each model more fuel-efficient.

As Roland Hwang, transportation program director for the Natural Resources Defense Council, explains, "There is no incentive for automobile companies to downsize to meet these new standards." Given that small cars must bear most of the burden of high gas mileage, you could argue the new regulations are "a disincentive to downsize," Hwang says.

But it's not just because big cars are going nowhere that conservative critics are riding shotgun with empty barrels. For years, physicists, road safety experts and auto designers have shown that big vehicles are not necessarily safer than smaller ones. Of course, nobody would debate that a head-on collision between a Chevy Tahoe and a Smart Car is going to favor the Tahoe. But that hypothetical crackup does not represent the ecology of the roads, where the truth of auto safety resides.

Outside the lab, many factors, including road conditions and driver behavior, influence when and why accidents occur. A vehicle's safety should be viewed not only in terms of how it protects its own occupants, but how likely it is to maim or kill others in a crash. By that standard, SUVs and pickups are more dangerous than compacts. But you don't hear conservative commentators beating their breasts calling for more regulations to make those bigger vehicles more compatible with smaller ones on the road.

The Insurance Institute for Highway Safety, a nonprofit funded by the auto insurance industry, is a leading proponent of the idea that bigger is better. As Adrian Lund, the president of the institute, puts it: "If you have two cars with the same safety technology in them, the one that is larger and heavier is going to protect you better, that is physics. It's just physics." So, is it time to throw a few hundred pounds of bricks in the back of that SmartForTwo? Not so fast.

Marc Ross, emeritus professor of physics at the University of Michigan, argues that the driving picture is more nuanced. "A simple rule of thumb, like 'It's bigger or heavier, so it must be safer,' buys you very little," he says. "It sounds like it's physics. But I'm a physicist, and I'll tell you that's not right. It's the structure and safety features that have been added on."

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Ross and Tom Wenzel, a research scientist with Lawrence Berkeley National Laboratory, have analyzed crash fatality rates. They looked at two factors: the risk that particular models pose to their own drivers and to drivers in other models. Viewed through this prism, many minivans are safe, while pickup trucks are off-the-charts menacing, both to their own drivers and to others on the road. That's confirmed by other research. One study found that the Ford F-350 presents nearly seven times the risk to other drivers as the Dodge Caravan, a minivan, as Tom Vanderbilt reports in "Traffic."

But importantly, the safety records of different models within the same size class can vary widely. For instance, the Volkswagen Beetle and (the late) Plymouth Neon are both subcompacts, but a Beetle driver is much safer than a Neon driver, according to their data. And Beetle drivers fared better than those of the much larger Ford Ranger. So much for bigger is always better.

If any broad rule of thumb applies for assessing vehicles' relative safety, it's that more expensive vehicles tend to be safer than cheaper ones, because they're better designed and tricked-out with innovative safety features and technologies. "The correlation to safety is with the cost of the vehicle, much more than size or weight," says Ross.

When it comes to safety on the road today, not all models are created equal. "There is a wide range in the fatality rate of small cars," says Wenzel. "The worst of them have three or four times the fatality rates as the safest. When you lump them together as a group, they'll have a higher fatality rate than larger cars. But the safest individual subcompact models have as low or lower risk than some larger vehicles."

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We spend most of our time on the road with other cars, rather than driving alone on some isolated highway. (Sixty-eight percent of crashes involve multiple cars.) So safety must be considered in ecological terms, on the impact one driver has on another, not to mention on pedestrians, bicyclists and animals. In those terms, heavy cars are more hazardous to our health on the roads. "As a vehicle gets heavier, it may protect its own occupants better, but it can also cause more damage," says Lund.

In industry parlance, many big vehicles, notably SUVs and pickups, are known as "aggressive." And that aggressiveness has more to do with the height of the vehicle than its weight, according to Ross. "If you have a vehicle which has a high front, which lots of pickups and SUVs do, that's a killer for people in another vehicle, particularly in a car. The weight has been thought to be really important, and it's not as important." Or, as Lund puts it, "Whenever two vehicles strike each other, the one that ends up on top, is a little higher, usually wins that crash."

Automakers are not required by law to try to make larger vehicles more compatible with smaller ones. But many have recently voluntarily introduced lower bumper heights to try to ensure that bumper hits bumper in crashes. Wenzel adds that the stiffness of the front of a truck is particularly dangerous, as it ramrods through cars. "That's what's causing a lot of fatalities in crashes between cars and trucks," he says. He advocates that the feds institute regulations to make sure some vehicles aren't imposing greater risks on others on the road.

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When you consider safety in terms of not just how a vehicle protects its occupants, but everyone else it might smash into, you get a different picture. Euro NCAP, the organization that assesses the safety of new cars in Europe, recently rated six new cars, and among their criteria was "pedestrian safety." It gave high marks to several diminutive mini models, such as the Kia Soul and the Hyundai i20. "Many claim that the weight and size of a car is the only criteria for safety," said Michiel van Ratingen, secretary general of Euro NCAP, in a statement about the ratings. "We believe that there are other aspects of safety that are just as important. The smaller cars we tested whose results are released today show that size should not stand in the way of all-round safety."

That's not to say that the relative weight of the vehicles is never important in crashes. Sometimes it is. When two vehicles collide, a seat-belted driver can be seriously injured one of three ways: when he hits a surface inside his own vehicle, like the dashboard; when part of the other vehicle intrudes and hits him; or from the sheer force of seat belts, or airbags restraining the body, which alone can cause serious injury.

It's in the last type of harm that the relative weights of the vehicle plays a role, because there will be more force acting on the occupants of the smaller vehicle. But when Ross analyzed crashes involving seat-belted drivers that weren't rollovers, he found that only 25 percent of serious injuries occurred the third way in frontal crashes, and only 12 percent in side impact crashes. "Adding weight to vehicles may reduce the number of fatalities or serious injuries caused by deceleration," says Wenzel, "but it's a small fraction."

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And modern cars and trucks are designed to crumple when they collide, not bounce like a billiard ball, so crush zones absorb some of the momentum. "When you have a vehicle crashing, they're designed to fail in very particular ways, and dissipate the kinetic energy of the crash by deformation, noise and heat," says Mike Simpson, a transportation analyst at the Rocky Mountain Institute. He argues vehicles could get lighter without losing size by employing advanced aerodynamics and more parts made of aluminum, carbon-fiber composites and thermoplastic composites.

Also, in certain types of crashes, a heavy vehicle can imperil the vehicle's occupants. With a higher center of gravity, SUVs are more prone to roll over than cars. If they do roll over, all that weight is suddenly resting on the roof, at risk of crushing the occupants. The feds recently introduced tougher regulations to strengthen vehicle roofs to try to prevent deaths during rollovers.

But a vehicle can't get into a crash without a driver behind the wheel, and the supposedly safest vehicle in the world can't prevent careless driving. "Assigning risk based purely on 'vehicle factors' is limiting, because it neglects the idea of who is driving the vehicle, and how it is being driven," writes Vanderbilt. In "Traffic," he quotes Bill Prosser, veteran highway designer, Federal Highway Administration, who admits that for all the human ingenuity and technology poured into automotive and highway safety, there is one thing engineers can't control. "There are three things out there that affect the way a highway operates: the design, the vehicle and the driver," Prosser says. "We can't control the driver, whether they're good, bad or indifferent."

As we know, people buy cars to express themselves and suit their lifestyles -- and drive them accordingly. The young executive buys a BMW to drive fast. One reason minivans have such an excellent safety record is they're likely to be driven by risk-averse parents shuttling kids to Little League at 11 a.m. on a Saturday. The safest car in terms of its features or design or even size cannot overcome boneheaded driver behavior, or perilous conditions. "Many of the small cars are inexpensive cars, and they're driven by young and inexperienced drivers," says Dan Becker, director of the Safe Climate Campaign, which is a project of the Center for Auto Safety.

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And let's not forget the twisted psychology of how driving may be affected by how safe we perceive our vehicle to be. Ironically, if you feel safe because you're high up in an SUV with so much metal around you, you may be inclined to drive faster and more aggressively, which puts you and everyone else on the road in danger. One London study of 40,000 vehicles found that SUV drivers were more likely to be driving while talking on a cellphone than car drivers, more likely to not be wearing a seat belt, and more likely to be talking on a cellphone while not wearing a seat belt! "The result, studies have argued, is that SUVs are overall no safer than medium or large passenger cars, and are less safe than minivans," writes Vanderbilt.

Instead of hijacking the debate about fuel economy with an erroneous sideshow about size, maybe pundits should brush up on how the automakers plan to meet the requirements. Automakers will likely use hybrid technologies and other innovations, such as direct-injection and turbocharging, according to John Voelcker, editor in chief of Green Car Reports, to improve both gas mileage and power. "What we are not going to see come true," Voelcker says, "is this notion, 'We'll only be able to drive golf carts.'"